[Qemu-ppc] [PULL 30/52] target-ppc: Bug Fix: mullw

[Alexander Graf]

From: Tom Musta <address@hidden>

For 64-bit implementations, the mullw result is the 64 bit product
of the sign-extended least significant 32 bits of the source
registers.

Fix the code to properly sign extend the source operands and produce
a 64 bit product.

Example:
R3 00000000002F37A0
R4 41C33D242F816715
mullw 3,3,4
R3 expected : 0008C3146AE0F020
R3 actual   : 000000006AE0F020 (without this patch)

Signed-off-by: Tom Musta <address@hidden>
Signed-off-by: Alexander Graf <address@hidden>
---
 target-ppc/translate.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index dc80b02..b19eb14 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -1128,9 +1128,20 @@ static void gen_mulhwu(DisasContext *ctx)
 /* mullw  mullw. */
 static void gen_mullw(DisasContext *ctx)
 {
+#if defined(TARGET_PPC64)
+    TCGv_i64 t0, t1;
+    t0 = tcg_temp_new_i64();
+    t1 = tcg_temp_new_i64();
+    tcg_gen_ext32s_tl(t0, cpu_gpr[rA(ctx->opcode)]);
+    tcg_gen_ext32s_tl(t1, cpu_gpr[rB(ctx->opcode)]);
+    tcg_gen_mul_i64(cpu_gpr[rD(ctx->opcode)], t0, t1);
+    tcg_temp_free(t0);
+    tcg_temp_free(t1);
+#else
     tcg_gen_mul_tl(cpu_gpr[rD(ctx->opcode)], cpu_gpr[rA(ctx->opcode)],
                    cpu_gpr[rB(ctx->opcode)]);
     tcg_gen_ext32s_tl(cpu_gpr[rD(ctx->opcode)], cpu_gpr[rD(ctx->opcode)]);
+#endif
     if (unlikely(Rc(ctx->opcode) != 0))
         gen_set_Rc0(ctx, cpu_gpr[rD(ctx->opcode)]);
 }
-- 
1.8.1.4